Technology for lowering instantaneous power consumption of neural processing unit

ABSTRACT

A system may comprise a neural processing unit (NPU) including at least one memory and a plurality of processing elements (PEs) capable of performing operations for at least one artificial neural network (ANN) model. The plurality of PEs may include an adder, a multiplier, and an accumulator. The plurality of PEs may include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 10-2023-0061416 filed on May 12, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE Technical Field

The present disclosure relates to a technique for lowering instantaneous power consumption of a neural processing unit.

Background Art

Artificial intelligence (AI) is rapidly advancing. AI refers to artificially imitating human intelligence, that is, intelligence capable of recognition, classification, inference, prediction, control/decision making, and the like.

In recent times, to enhance the computational speed for artificial intelligence (AI), a neural processing unit (NPU) has been developed.

Depending on the specific AI service requirements, different types of artificial neural network (ANN) models may exist. For instance, when processing an image or video, a CNN type artificial neural network model can be employed for tasks like object classification, object detection, object tracking, and the like.

Generally, each layer of an artificial neural network model involves varying levels of computation.

In particular, when a specific layer requires a significant increase in computational operations, it can lead to an instantaneous surge in power consumption.

SUMMARY OF THE DISCLOSURE

Artificial neural network operation has a data-intensive characteristic. In particular, artificial neural network calculations require parallel processing calculations. In other words, the artificial neural network operation has a characteristic in that the processing speed is lowered if a large amount of data cannot be processed in parallel at a high speed at the same time.

Accordingly, the inventors of the present disclosure developed a neural processing unit specialized for artificial neural network calculation. The inventors of the present disclosure have attempted to improve the parallel processing performance of the neural processing unit by increasing the number of a plurality of processing elements of the neural processing unit. In addition, the inventors of the present disclosure have attempted to develop a neural processing unit capable of low-power operation.

Meanwhile, a power supply unit of a neural processing unit specialized for low-power operation installed in an edge device may have relatively low power supply capability compared to a power supply unit of a graphic processing unit (GPU) operating in a server or personal computer (PC). In addition, capacitance of a power supply unit of a neural processing unit specialized for low-power operation installed in an edge device may be insufficient to handle peak power supply.

However, the inventors of the present disclosure have recognized that as the number of processing elements of the neural processing unit specialized for low-power operation increases, the degree of instantaneously fluctuating supply voltage may increase. In other words, the required amount of instantaneous power supply of the neural processing unit may be proportional to the number of operating processing elements. In addition, the amount of computation of the artificial neural network model varies considerably for each layer. Therefore, the number of processing elements operating in parallel may be different according to the amount of computation of the layer of the artificial neural network model. That is, when many processing elements operate at the same time, the voltage of the power supply unit of the neural processing unit may drop instantaneously.

Accordingly, the inventors of the present disclosure recognized that it is necessary to improve the stability of a supply voltage of a neural processing unit specialized in artificial neural network operation even when the number of processing elements increases.

Accordingly, the disclosures in the present disclosure are aimed at disclosing technical solutions for stabilizing the fluctuation of the supply voltage of the supply power unit.

According to an example of the present disclosure, a system may be provided. The system may comprise a neural processing unit (NPU) including at least one memory and a plurality of processing elements (PEs) capable of performing operations for at least one artificial neural network (ANN) model. The plurality of PEs may include an adder, a multiplier, and an accumulator. The plurality of PEs may include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.

The first portion may be a rising edge of the clock signal, and the second portion may be a falling edge of the clock signal.

A first output from the first group of PEs and a second output from the second group of PEs may be transmitted based on the first portion of the clock signal.

At least one reference phase of at least one group of the first group of PEs and the second group of PEs may be converted from the rising edge to the falling edge of the clock signal or converted from the falling edge to the rising edge of the clock signal.

A reference phase of the second group of PEs may be converted from the second portion to the first portion of the clock signal.

An output port of the second group of PEs may be connected to a delay buffer. The delay buffer may be configured to perform conversion from the rising edge to the falling edge of the clock signal or from the falling edge to the rising edge of the clock signal.

An output port of the second group of PEs may be connected to a delay buffer. The delay buffer may be configured to convert the second portion of the clock signal to the first portion of the clock signal or convert the first portion of the clock signal to the second portion of the clock signal.

The NPU may include a special function unit (SFU) connected to output ports of the PEs of the first and second groups.

The SFU may be coupled to the at least one memory.

The plurality of PEs of the first and second groups may be time-varying.

According to an example of the present disclosure, a SoC may be provided. The SoC may comprise a first circuit arranged as at least one memory; and a second circuit arranged as a plurality of processing elements (PEs) capable of performing operations for at least one of artificial neural network (ANN) models. The plurality of PEs may include an adder, a multiplier, and an accumulator. The plurality of PEs may include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.

The first portion may be a rising edge of the clock signal, and the second portion may be a falling edge of the clock signal.

A first output from the first group of PEs and a second output from the second group of PEs may be transmitted based on the first portion of the clock signal.

At least one reference phase of at least one group of the first group of PEs and the second group of PEs may be converted from the rising edge to the falling edge of the clock signal or converted from the falling edge to the rising edge of the clock signal.

A reference phase of the second group of PEs may be converted from the second portion to the first portion of the clock signal.

An output port of the second group of PEs may be connected to a delay buffer. The delay buffer may be configured to perform conversion from the rising edge to the falling edge of the clock signal or from the falling edge to the rising edge of the clock signal.

An output port of the second group of PEs may be connected to a delay buffer. The delay buffer may be configured to convert the second portion of the clock signal to the first portion of the clock signal or convert the first portion of the clock signal to the second portion of the clock signal.

According to an example of the present disclosure, a method is provided. The method of operating a NPU may comprise generating a clock signal for driving the NPU including a plurality of processing elements (PEs); operating a first group of PEs of the plurality of PEs on a first portion of the clock signal; and operating a second group of PEs of the plurality of PEs on a second portion of the clock signal. The plurality of PEs may include an adder, a multiplier, and an accumulator.

The first portion may be a rising edge of the clock signal, and the second portion may be a falling edge of the clock signal.

A first output from the first group of PEs and a second output from the second group of PEs may be transmitted based on the first portion of the clock signal.

According to examples of the present disclosure, artificial neural network operations are distributed based on different portions of a clock signal, which has the advantage of reducing peak power consumption.

According to the examples of the present disclosure, artificial neural network operations are distributed based on different portions of a clock signal, thereby improving the stability of a voltage supplied to a neural processing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic conceptual diagram illustrating an exemplary artificial neural network model.

FIG. 2A is a diagram for explaining the basic structure of a convolutional neural network (CNN).

FIG. 2B is a comprehensive diagram showing the operation of a convolutional neural network.

FIG. 3 is a schematic conceptual diagram illustrating a neural processing unit according to the present disclosure.

FIG. 4A is a schematic conceptual diagram illustrating one processing element among a plurality of processing elements that may be applied to the present disclosure.

FIG. 4B is a schematic conceptual diagram illustrating an SFU that can be applied to the present disclosure.

FIG. 5 is an exemplary diagram illustrating a modified example of the NPU 100 shown in FIG. 3 .

FIG. 6A is an exemplary view showing the size of data for each layer in the exemplary artificial neural network model.

FIG. 6B is an exemplary table showing the size of data for each layer in the exemplary artificial neural network model shown in FIG. 6A.

FIG. 7A is an exemplary diagram showing the structure of an NPU according to an example of the first disclosure of the present disclosure.

FIG. 7B is an exemplary view showing the structure of an NPU according to another example of the first disclosure of the present disclosure.

FIG. 8A is an exemplary diagram illustrating a structure of an SoC according to an example of the second disclosure of the present disclosure.

FIG. 8B is an exemplary diagram illustrating a structure of an SoC according to another example of the second disclosure of the present disclosure.

FIG. 9A is an exemplary view showing the structure of a system according to an example of the third disclosure of the present disclosure.

FIG. 9B is an exemplary view showing the structure of a system according to an example of the third disclosure of the present disclosure.

FIG. 10 is an exemplary diagram illustrating an operation method of an NPU according to the disclosures of the present disclosure.

FIG. 11 is an exemplary diagram illustrating an operation method of an NPU according to the disclosures of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT

Specific structural or step-by-step descriptions for the embodiments according to the concept of the present disclosure disclosed in the present disclosure or application are merely illustrative for the purpose of describing the embodiments according to the concept of the present disclosure. The examples according to the concept of the present disclosure may be carried out in various forms and are not interpreted as that the present disclosure is limited to the examples described in the present disclosure or application.

Various modifications and changes may be applied to the examples in accordance with the concept of the present disclosure and the examples may have various forms so that the examples will be described in detail in the specification or the application with reference to the drawings. However, it should be understood that the examples according to the concept of the present disclosure is not limited to the specific examples, but includes all changes, equivalents, or alternatives which are in line with the spirit and technical scope of the present disclosure.

Terminologies such as first and/or second may be used to describe various components but the components are not limited by the above terminologies. The above terminologies are used to distinguish one component from the other component, for example, a first component may be referred to as a second component without departing from a scope in accordance with the concept of the present invention and similarly, a second component may be referred to as a first component.

It should be understood that, when it is described that an element is “coupled” or “connected” to another element, the element may be directly coupled or directly connected to the other element or coupled or connected to the other element through a third element. In contrast, when it is described that an element is “directly coupled” or “directly connected” to another element, it should be understood that no element is present therebetween. Other expressions which describe the relationship between components, for example, “between,” “adjacent to,” and “directly adjacent to” should be interpreted in the same manner.

Terminologies used in the present disclosure are used only to describe specific examples, and are not intended to limit the present disclosure. A singular form may include a plural form if there is no clearly opposite meaning in the context. In the present disclosure, it should be understood that terms “include” or “have” indicate that a feature, a number, a step, an operation, a component, a part, or a combination thereof described in the present disclosure is present, but do not exclude a possibility of presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof, in advance.

If it is not contrarily defined, all terms used herein including technological or scientific terms have the same meaning as those generally understood by a person with ordinary skill in the art. Terminologies which are defined in a generally used dictionary should be interpreted to have the same meaning as the meaning in the context of the related art but are not interpreted as an ideally or excessively formal meaning if it is not clearly defined in the present disclosure.

In describing examples, descriptions of technical contents that are well known in the art to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. The omission is to convey the gist of the present disclosure more clearly without the obscuration of the unnecessary description of well-known technical details.

Definitions of Terms

Here, in order to help the understanding of the disclosure proposed in the present disclosure, terminologies used in the present disclosure will be defined in brief.

NPU is an abbreviation for a neural processing unit and refers to a processor specialized for an operation of an artificial neural network model separately from the central processor (CPU).

ANN is an abbreviation for an artificial neural network and refers to a network which connects nodes in a layered structure by imitating the connection of the neurons in the human brain through a synapse to imitate the human intelligence.

DNN is an abbreviation for a deep neural network and may mean that the number of hidden layers of the artificial neural network is increased to implement higher artificial intelligence.

CNN is an abbreviation for a convolutional neural network and is a neural network which functions similar to the image processing performed in a visual cortex of the human brain. The convolutional neural network is known to be appropriate for image processing and is known to be easy to extract features of input data and identify the pattern of the features.

Hereinafter, the present disclosure will be described in detail by explaining examples of the present disclosure with reference to the accompanying drawings.

<Artificial Intelligence>

Humans are equipped with intelligence capable of recognition, classification, inference, prediction, control/decision making, and the like. Artificial intelligence (AI) refers to the artificial imitation of human intelligence.

The human brain consists of numerous nerve cells called neurons. Each neuron is connected to hundreds to thousands of other neurons through connections called synapses. In order to imitate human intelligence, modeling the operating principle of biological neurons and the connection between neurons is called an artificial neural network model. In other words, an artificial neural network is a system in which nodes that imitate neurons are connected in a layer structure.

These artificial neural network models are divided into ‘single-layer neural networks’ and ‘multi-layer neural network’ according to the number of layers. A typical multi-layer neural network consists of an input layer, a hidden layer, and an output layer. (1) The input layer is a layer that receives external data, and the number of neurons in the input layer is the same as the number of input variables. (2) The hidden layer is located between the input layer and the output layer, receives signals from the input layer, extracts characteristics, and transfers them to the output layer. (3) The output layer receives signals from the hidden layer and outputs the result. The input signal between neurons is multiplied by each connection weight having a value between 0 and 1 and summed. If this sum is greater than the neuron's threshold, the neuron is activated and implemented as an output value through an activation function.

Meanwhile, in order to implement higher artificial intelligence, an artificial neural network in which the number of hidden layers is increased is called a deep neural network (DNN).

DNNs are being developed in various structures. For example, a convolutional neural network (CNN), which is an example of DNN, is known to be easy to extract features of an input value (video or image) and identify a pattern of the extracted output value. A CNN may be configured in a form in which a convolution operation, an activation function operation, a pooling operation, and the like are processed in a specific order.

For example, in each layer of the DNN, parameters (i.e., input values, output values, weights or kernels, and the like) may be a matrix composed of a plurality of channels. Parameters can be processed in the NPU by convolution or matrix multiplication. In each layer, an output value that has been processed is generated.

For example, a transformer is a DNN based on attention technology. Transformers utilize a number of matrix multiplication operations. The transformer may obtain an output value of attention (Q, K, V) by using parameters such as an input value and a query (Q), a key (K), and a value (V). The transformer can process various inference operations based on the output value (i.e., attention (Q, K, V)). Transformers tend to show better inference performance than CNNs.

FIG. 1 illustrates an exemplary artificial neural network model.

Hereinafter, an operation of an exemplary artificial neural network model 110 a which may operate in the NPU 100 will be explained.

The exemplary artificial neural network model 110 a of FIG. 1 may be an artificial neural network trained to perform various inference functions such as object detection or voice recognition.

The artificial neural network model 110 a may be a deep neural network (DNN).

However, the artificial neural network model 110 a according to the examples of the present disclosure is not limited to the deep neural network.

For example, the artificial neural network model can be a model such as Transformer, YOLO (You Only Look Once), CNN, PIDNet, BiseNet, RCNN, VGG, VGG16, DenseNet, SegNet, DeconvNet, DeepLAB V3+, U-net, SqueezeNet, Alexnet, ResNet18, MobileNet-v2, GoogLeNet, Resnet-v2, Resnet50, Resnet101, Inception-v3, and the like. However, the artificial neural network model 110 a may be an ensemble model based on at least two different models.

Hereinafter, an inference process by the exemplary artificial neural network model 110 a will be described.

The artificial neural network model 110 a may be an exemplary deep neural network model including an input layer 110 a-1, a first connection network 110 a-2, a first hidden layer 110 a-3, a second connection network 110 a-4, a second hidden layer 110 a-5, a third connection network 110 a-6, and an output layer 110 a-7. However, the present disclosure is not limited only to the artificial neural network model illustrated in FIG. 1 . The first hidden layer 110 a-3 and the second hidden layer 110 a-5 may also be referred to as a plurality of hidden layers.

The input layer 110 a-1 may exemplarily include input nodes x1 and x2. That is, the input layer 110 a-1 may include information about two input values.

For example, the first connection network 110 a-2 may include information about six weight values for connecting nodes of the input layer 110 a-1 to nodes of the first hidden layer 110 a-3, respectively. Each weight value is multiplied with the input node value, and an accumulated value of the multiplied values is stored in the first hidden layer 110 a-3. Here, the nodes and weights may be referred to as parameters.

For example, the first hidden layer 110 a-3 may include nodes a1, a2, and a3. That is, the first hidden layer 110 a-3 may include information about three node values.

The first processing element PE1 of FIG. 3 may perform the MAC operation of the a1 node.

The second processing element PE2 of FIG. 3 may perform the MAC operation of the a2 node.

The third processing element PE3 of FIG. 3 may perform the MAC operation of the a3 node.

For example, the second connection network 110 a-4 may include information about nine weight values for connecting nodes of the first hidden layer 110 a-3 to nodes of the second hidden layer 110 a-5, respectively. The weight value of the second connection network 110 a-4 is multiplied with the node value input from the corresponding first hidden layer 110 a-3 and the accumulated value of the multiplied values is stored in the second hidden layer 110 a-5.

For example, the second hidden layer 110 a-5 may include nodes b1, b2, and b3. That is, the second hidden layer 110 a-5 may include information about three node values.

The fourth processing element PE4 of FIG. 3 may process the operation of the b1 node.

The fifth processing element PE5 of FIG. 3 may process the operation of node b2.

The sixth processing element PE6 of FIG. 3 may process the operation of node b3.

For example, the third connection network 110 a-6 may include information about six weight values which connect nodes of the second hidden layer 110 a-5 and nodes of the output layer 110 a-7, respectively. The weight value of the third connection network 110 a-6 is multiplied with the node value input from the second hidden layer 110 a-5, and the accumulated value of the multiplied values is stored in the output layer 110 a-7.

For example, the output layer 110 a-7 may include nodes y1 and y2. That is, the output layer 110 a-7 may include information about two node values.

The seventh processing element PE7 of FIG. 3 may process the operation of node y1.

The eighth processing element PE8 of FIG. 3 may process the operation of node y2.

FIG. 2A is a diagram for explaining the basic structure of a convolutional neural network (CNN).

Referring to FIG. 2A, an input image may be displayed as a two-dimensional matrix composed of rows of a specific size and columns of a specific size. An input image may have a plurality of channels, where the channels may represent the number of color components of the input data image.

The convolution process means performing a convolution operation with a kernel while traversing the input image at specified intervals.

A convolutional neural network may have a structure in which an output value (convolution or matrix multiplication) of a current layer is transferred as an input value of a next layer.

For example, convolution is defined by two main parameters (input feature map and kernel). Parameters may include input feature maps, output feature maps, activation maps, weights, kernels, attention (Q, K, V) values, and the like.

Convolution slides the kernel window over the input feature map. The step size by which the kernel slides over the input feature map is called the stride.

After convolution, pooling may be applied. In addition, a fully-connected (FC) layer may be disposed at an end of the convolutional neural network.

FIG. 2B is a comprehensive diagram showing the operation of a convolutional neural network.

Referring to FIG. 2B, an input image is exemplarily represented as a two-dimensional matrix having a size of 6×6. In addition, FIG. 2B exemplarily illustrates three nodes, channel 1, channel 2, and channel 3.

First, the convolution operation will be described.

The input image (shown as an example of size 6×6 in FIG. 2B) is convolved with a kernel 1 (shown as an example of size 3×3 in FIG. 2B) for channel 1 at the first node, resulting in the output feature map 1 (shown as an example of size 4×4 in FIG. 2B). Similarly, the input image (shown as an example of size 6×6 in FIG. 2B) is convolved with a kernel 2 (shown as an example of size 3×3 in FIG. 2B) for channel 2 at the second node, resulting in the output feature map 2 (shown as an example of size 4×4 in FIG. 2B). Additionally, the input image is convolved with a kernel 3 (shown as an example of size 3×3 in FIG. 2B) for channel 3 at the third node, resulting in the output feature map 3 (shown as an example of size 4×4 in FIG. 2B).

To process each convolution, the processing elements PE1 to PE12 of the NPU 100 are configured to perform a MAC operation.

Next, the operation of the activation function will be described.

The feature map 1, the feature map 2, and the feature map 3 (which are represented as 4×4 examples in FIG. 2B) generated from convolutional operations can be subjected to activation functions. The output after the activation function is applied may have a size of 4×4, for example.

Next, a pooling operation will be described.

Feature map 1, feature map 2, and feature map 3 output from the activation function (each size is exemplarily represented as 4×4 in FIG. 2B) are input to three nodes. Pooling may be performed by receiving feature maps output from the activation function as inputs. The pooling may reduce the size or emphasize a specific value in the matrix. Pooling methods include maximum pooling, average pooling, and minimum pooling. Maximum pooling is used to collect the maximum values in a specific region of the matrix, and average pooling can be used to find the average within a specific region.

In the example of FIG. 2B, it is shown that a feature map having a size of 4×4 is reduced to a size of 2×2 by pooling.

Specifically, the first node receives feature map 1 for channel 1 as an input, performs pooling, and outputs, for example, a 2×2 matrix. The second node receives feature map 2 for channel 2 as an input, performs pooling, and outputs, for example, a 2×2 matrix. The third node receives feature map 3 for channel 3 as an input, performs pooling, and outputs, for example, a 2×2 matrix.

The aforementioned convolution, activation function, and pooling are repeated, and finally, it can be output as fully connected. The corresponding output may be input again to an artificial neural network for image recognition. However, the present disclosure is not limited to the sizes of feature maps and kernels.

The CNN described so far is the most used method in the field of computer vision among various deep neural network (DNN) methods. In particular, CNNs have shown remarkable performance in various research areas performing various tasks such as image classification and object detection.

<Required Hardware Resources for ANN>

FIG. 3 is a schematic conceptual diagram illustrating a neural processing unit according to the present disclosure.

Referring to FIG. 3 , a neural processing unit (NPU) 100 is a processor specialized to perform an operation for an artificial neural network.

The artificial neural network refers to a network that consists of artificial neurons which, when receiving various inputs or entry stimulations, multiply a weight by the inputs or stimulations, add the multiplied values, and convert a value obtained by additionally adding a deviation using an active function to transmit. The artificial neural network trained as described above may be used to output an inference result from input data.

The NPU 100 may be a semiconductor device implemented by an electric/electronic circuit. The electric/electronic circuit may refer to a circuit including a large number of electronic elements (transistors, capacitors, and the like).

In the case of a transformer and/or CNN-based artificial neural network model, the NPU 100 may select and process matrix multiplication operations, convolution operations, and the like according to the architecture of the artificial neural network.

For example, in each layer of a convolutional neural network (CNN), an input feature map corresponding to input data and a kernel corresponding to weights may be a matrix composed of a plurality of channels. A convolution operation between the input feature map and the kernel is performed, and a convolution operation and a pooled output feature map are generated in each channel. An activation map of a corresponding channel is generated by applying an activation function to the output feature map. After that, pooling for the activation map may be applied. Here, the activation map may be collectively referred to as an output feature map.

However, examples of the present disclosure are not limited thereto, and the output feature map means that a matrix multiplication operation or a convolution operation is applied.

To elaborate, the output feature map according to the examples of the present disclosure should be interpreted in a comprehensive sense. For example, the output feature map may be a result of a matrix multiplication operation or a convolution operation. Accordingly, the plurality of processing elements 110 may be modified to further include processing circuitry for additional algorithms.

The NPU 100 may be configured to include a plurality of processing elements 110 for processing convolution and matrix multiplication necessary for the above-described artificial neural network operation.

The NPU 100 may be configured to include each processing circuit optimized for matrix-multiplication operation, convolution operation, activation function operation, pooling operation, stride operation, batch-normalization operation, skip-connection operation, concatenation operation, quantization operation, clipping operation, padding operation, and the like required for the above-described artificial neural network operation.

For example, the NPU 100 may be configured to include the SFU 150 for processing at least one of activation function operation, pooling operation, stride operation, batch-normalization operation, skip-connection operation, concatenation operation, quantization operation, clipping operation, and padding operation for the above-described algorithms.

The NPU 100 may include a plurality of processing elements (PE) 110, an NPU internal memory 120, an NPU controller 130, and an NPU interface 140. Each of the plurality of processing elements 110, the NPU internal memory 120, the NPU controller 130, and the NPU interface 140 may be a semiconductor circuit to which a large number of the electronic elements are connected. Therefore, some of electronic elements may be difficult to identify or be distinguished with the naked eye, but may be identified only by a circuitry operation.

For example, an arbitrary circuit may operate as a plurality of the processing elements 110, or may operate as an NPU controller 130. The NPU controller 130 may be configured to perform the function of the control unit that is configured to control the artificial neural network inference operation of the NPU 100.

The NPU 100 may include a NPU controller 130 including an NPU internal memory 120 configured to store parameters of an artificial neural network model that can be inferred from the plurality of processing elements 110 and the SFU 150 and a scheduler configured to control operation schedules of the plurality of processing elements 110, the SFU 150, and the NPU internal memory 120.

The NPU 100 may be configured to process the feature map corresponding to the encoding and decoding method using scalable video coding (SVC) or scalable feature-map coding (SFC).

The plurality of processing elements 110 may perform a portion of the operations for an artificial neural network.

SFU 150 may perform another portion of the operation for the artificial neural network.

The NPU 100 may be configured to hardware-accelerate the computation of the artificial neural network model using the plurality of processing elements 110 and the SFU 150.

The NPU interface 140 may communicate with various components connected to the NPU 100, for example, memories, via a system bus.

The NPU controller 130 may include a scheduler configured to control the operation of multiple processing elements 110 for inference operations of a neural processing unit 100, as well as operations of the SFU 150 and reading and writing order of the internal memory 120 of the NPU.

The scheduler in the NPU controller 130 may be configured to control the plurality of processing elements 110, the SFU 150, and the NPU internal memory 120 based on data locality information or structure information of the artificial neural network model.

The scheduler in the NPU controller 130 may analyze or receive analyzed information on a structure of an artificial neural network model which may operate in the plurality of processing elements 110. For example, data of the artificial neural network, which may be included in the artificial neural network model may include node data (i.e., feature map) of each layer, data on a layout of layers, locality information of layers or information about the structure, and at least a portion of weight data (i.e., weight kernel) of each of connection networks connecting the nodes of the layers. The data of the artificial neural network may be stored in a memory provided in the NPU controller 130 or the NPU internal memory 120.

The scheduler in the NPU controller 130 may schedule an operation order of the artificial neural network model to be processed by an NPU 100 based on the data locality information or the information about the structure of the artificial neural network model.

The scheduler in the NPU controller 130 may acquire a memory address value in which feature map of a layer of the artificial neural network model and weight data are stored based on the data locality information or the information about the structure of the artificial neural network model. For example, the scheduler in the NPU controller 130 may acquire the memory address value of the feature map of the layer of the artificial neural network model and the weight data which are stored in the memory. Accordingly, the scheduler in the NPU controller 130 may acquire feature map of a layer and weight data of an artificial neural network model to be driven from the main memory, to store the acquired data in the NPU internal memory 120.

Feature map of each layer may have a corresponding memory address value.

Each of the weight data may have a corresponding memory address value.

The scheduler in the NPU controller 130 may schedule an operation order of the plurality of processing elements 110 based on the data locality information or the information about the structure of the artificial neural network model, for example, the layout information of layers of the artificial neural network or the information about the structure of the artificial neural network model.

The scheduler in the NPU controller 130 may schedule based on the data locality information or the information about the structure of the artificial neural network model so that the NPU scheduler may operate in a different way from a scheduling concept of a normal CPU. The scheduling of the normal CPU operates to provide the highest efficiency in consideration of fairness, efficiency, stability, and reaction time. That is, the normal CPU schedules to perform the most processing during the same time in consideration of a priority and an operation time.

A conventional CPU uses an algorithm which schedules a task in consideration of data such as a priority or an operation processing time of each processing.

In contrast, the scheduler in the NPU controller 130 may control the NPU 100 according to a determined processing order of the NPU 100 based on the data locality information or the information about the structure of the artificial neural network model.

Moreover, the scheduler in the NPU controller 130 may operate the NPU 100 according to the determined the processing order based on the data locality information or the information about the structure of the artificial neural network model and/or data locality information or information about a structure of the NPU 100 to be used.

However, the present disclosure is not limited to the data locality information or the information about the structure of the NPU 100.

The scheduler in the NPU controller 130 may be configured to store the data locality information or the information about the structure of the artificial neural network.

That is, even though only the data locality information or the information about the structure of the artificial neural network of the artificial neural network model is utilized, the scheduler in the NPU controller 130 may determine a processing sequence.

Moreover, the scheduler in NPU controller 130 may determine the processing order of the NPU 100 by considering the data locality information or the information about the structure of the artificial neural network model and data locality information or information about a structure of the NPU 100. Furthermore, it is possible to optimize the processing according to the determined processing order.

The plurality of processing elements 110 refers to a configuration in which a plurality of processing elements PE1 to PE12 that is configured to operate feature map and weight data of the artificial neural network is deployed. Each processing element may include a multiply and accumulate (MAC) operator and/or an arithmetic logic unit (ALU) operator, but the examples according to the present disclosure are not limited thereto.

Each processing element may further include an additional special function unit for processing the additional special functions.

For example, it is also possible for the processing element PE to be modified and implemented to further include a batch-normalization unit, an activation function unit, an interpolation unit, and the like.

The SFU 150 may include each processing circuit configured to select and process activation function operation, pooling operation, stride operation, batch-normalization operation, skip-connection operation, concatenation operation, quantization operation, clipping operation, padding operation, and the like according to the architecture of the artificial neural network. That is, the SFU 150 may include a plurality of special function arithmetic processing circuit units.

Even though FIG. 5 illustrates a plurality of processing elements as an example, operators implemented by a plurality of multiplier and adder trees may also be configured to be deployed in parallel in one processing element, instead of the MAC. In this case, the plurality of processing elements 110 may also be referred to as at least one processing element including a plurality of operators.

The plurality of processing elements 110 is configured to include a plurality of processing elements PE1 to PE12. The plurality of processing elements PE1 to PE12 of FIG. 5 is merely an example for the convenience of description and the number of the plurality of processing elements PE1 to PE12 is not limited to 12 or any other integer numbers. A size or the number of processing element arrays 110 may be determined by the number of the plurality of processing elements PE1 to PE12. The size of the plurality of processing elements 110 may be implemented by an N×M matrix. Here, N and M are integers greater than zero. The plurality of processing elements 110 may include N×M processing elements. That is, one or more processing elements may be provided.

A number of the plurality of processing elements 110 may be designed in consideration of the characteristic of the artificial neural network model in which the NPU 100 operates.

The plurality of processing elements 110 is configured to perform a function such as addition, multiplication, and accumulation required for the artificial neural network operation. In other words, the plurality of processing elements 110 may be configured to perform a multiplication and accumulation (MAC) operation.

Hereinafter, a first processing element PE1 among the plurality of processing elements 110 will be explained with an example.

FIG. 4A illustrates one processing element among a plurality of processing elements that may be applied to the present disclosure.

As illustrated in FIG. 3 , the NPU 100 according to the examples of the present disclosure may include the plurality of processing elements 110, the NPU internal memory 120 configured to store an artificial neural network model inferred from the plurality of processing elements 110, and the NPU controller 130 configured to control the plurality of processing elements 110 and the NPU internal memory 120 based on data locality information or information about a structure of the artificial neural network model. The plurality of processing elements 110 is configured to perform the MAC operation and the plurality of processing elements 110 is configured to quantize and output the MAC operation result, but the examples of the present disclosure are not limited thereto.

The NPU internal memory 120 may store all or a part of the artificial neural network model in accordance with the memory size and the data size of the artificial neural network model.

As illustrated in FIG. 4A, the first processing element PE1 may include a multiplier 111, an adder 112, an accumulator 113, and a bit quantizer 114. However, the examples according to the present disclosure are not limited thereto and the plurality of processing elements 110 may be modified in consideration of the operation characteristic of the artificial neural network.

The multiplier 111 multiplies input (N) bit data and (M) bit data. The operation value of the multiplier 111 is output as (N+M) bit data.

The multiplier 111 may be configured to receive one variable and one constant.

The accumulator 113 accumulates an operation value of the multiplier 111 and an operation value of the accumulator 113 using the adder 112 as many times as the number of (L) loops. Therefore, a bit width of data of an output unit and an input unit of the accumulator 113 may be output to (N+M+log 2(L)) bits. Here, L is an integer greater than zero.

When the accumulation is completed, the accumulator 113 is applied with an initialization reset to initialize the data stored in the accumulator 113 to zero, but the examples according to the present disclosure are not limited thereto.

The bit quantizer 114 may reduce the bit width of the data output from the accumulator 113. The bit quantizer 114 may be controlled by the NPU controller 130. The bit width of the quantized data may be output to (X) bits. Here, X is an integer greater than zero. According to the above-described configuration, the plurality of processing elements 110 is configured to perform the MAC operation and the plurality of processing elements 110 may quantize the MAC operation result to output the result. The quantization may have an effect that the larger the (L) loops, the smaller the power consumption. Further, when the power consumption is reduced, the heat generation may also be reduced. Additionally, when the heat generation is reduced, the possibility of the erroneous operation of the NPU 100 due to the high temperature may be reduced.

Output data (X) bits of the bit quantizer 114 may serve as node data of a subsequent layer or input data of a convolution. When the artificial neural network model is quantized, the bit quantizer 114 may be configured to be supplied with quantized information from the artificial neural network model. However, it is not limited thereto and the NPU controller 130 may also be configured to extract quantized information by analyzing the artificial neural network model. Accordingly, the output data (X) bit is converted to a quantized bit width to be output so as to correspond to the quantized data size. The output data (X) bit of the bit quantizer 114 may be stored in the NPU internal memory 120 with a quantized bit width.

The plurality of processing elements 110 of the NPU 100 according to an example of the present disclosure may include a multiplier 111, an adder 112, and an accumulator 113. The bit quantizer 114 may be selected according to whether quantization is applied or not.

FIG. 4B is a schematic conceptual diagram illustrating an SFU that can be applied to the present disclosure.

Referring to FIG. 4B, the SFU 150 may include several functional units. Each functional unit can be operated selectively. Each functional unit can be selectively turned on or turned off. That is, each functional unit can be set.

In other words, the SFU 150 may include various circuit units required for an artificial neural network inference operation.

For example, the circuit units of the SFU 150 may include a functional unit for skip-connection operation, a functional unit for activation function operation, a functional unit for pooling operation, a functional unit for quantization operation, a functional unit for non-maximum suppression (NMS) operation, a functional unit for integer to floating point conversion (INT to FP32) operation, a functional unit for a batch-normalization operation, a functional unit for an interpolation operation, a functional unit for a concatenation operation, a functional unit for a bias operation, and the like.

Functional units of the SFU 150 may be selectively turned on or off according to the data locality information of the artificial neural network model. Data locality information of an artificial neural network model may include turn-off of a corresponding functional unit or control information related to turn-off when an operation for a specific layer is performed.

An activated unit among functional units of the SFU 150 may be turned on. In this way, when some functional units of the SFU 150 are selectively turned off, power consumption of the NPU 100 can be reduced. Meanwhile, in order to turn off some functional units, power gating may be used. Alternatively, clock gating may be performed to turn off some functional units.

FIG. 5 illustrates a modified example of the neural processing unit 100 of FIG. 3 .

The NPU 100 of FIG. 5 is substantially the same as the NPU 100 exemplarily illustrated in FIG. 3 , except for the shown addition of the plurality of processing elements 110. Thus, redundant description will be omitted for the brevity.

The plurality of processing elements 110 exemplarily illustrated in FIG. 5 may further include register files RF1 to RF12, each of which corresponds to processing elements PE1 to PE12 respectively, in addition to a plurality of processing elements PE1 to PE12.

The plurality of processing elements PE1 to PE12 and the plurality of register files RF1 to RF12 of FIG. 5 are merely an example for the convenience of description and the number of the plurality of processing elements PE1 to PE12 and the plurality of register files RF1 to RF12 is not limited to 12 or any other integer number.

A size of, or the number of, processing element arrays 110 may be determined by the number of the plurality of processing elements PE1 to PE12 and the plurality of register files RF1 to RF12. The size of the plurality of processing elements 110 and the plurality of register files RF1 to RF12 may be implemented by an N×M matrix. Here, N and M are integers greater than zero.

An array size of the plurality of processing elements 110 may be designed in consideration of the characteristic of the artificial neural network model in which the NPU 100 operates. For additional explanation, the memory size of the register file may be determined in consideration of a data size, a required operating speed, and a required power consumption of the artificial neural network model to operate.

The register files RF1 to RF12 of the NPU 100 are static memory units which are directly connected to the processing elements PE1 to PE12. For example, the register files RF1 to RF12 may be configured by flip-flops and/or latches. The register files RF1 to RF12 may be configured to store the MAC operation value of the corresponding processing elements PE1 to PE12. The register files RF1 to RF12 may be configured to provide or be provided with the weight data and/or node data to or from the NPU internal memory 120.

It is also possible that the register files RF1 to RF12 are configured to perform a function of a temporary memory of the accumulator during MAC operation.

<Technical Difficulties Found by the Inventors of the Present Disclosure>

Depending on the purpose of the artificial intelligence service, several types of artificial neural network (ANN) models may exist. For example, when input data is an image or video, a CNN type artificial neural network model for object classification, object detection, object tracking, and the like in an image/video may be used for artificial intelligence service.

In general, an artificial neural network model may have a different amount of computation for each layer. This will be described with reference to FIGS. 6A and 6B.

FIG. 6A is an exemplary view showing the size of data for each layer in the exemplary artificial neural network model, and FIG. 6B is an exemplary table showing the size of data for each layer in the exemplary artificial neural network model shown in FIG. 6A.

The exemplary artificial neural network model shown in FIG. 6A is shown to be Mobilenet V1. The horizontal axis shown in FIG. 6A represents layers sequentially in the exemplary artificial neural network model, and the vertical axis represents the size of data.

Referring to layer 1 shown in FIG. 6A, it can be seen that the size of the output feature map OFMAP_SIZE is greater than the size of the input feature map IFMAP_SIZE.

The output feature map of the first layer is transferred to the second layer and becomes the input feature map of the second layer. When the calculation of the second layer is completed, an output feature map is output. The output feature map of the second layer is transferred to the third layer again, and becomes the input feature map of the third layer.

As such, the size of input data input to each layer and the size of an output feature map output from each layer may be different. Accordingly, the amount of calculation may be small in a certain layer, but the amount of calculation may be very large in another layer. In this way, as the amount of computation per layer is greatly fluctuated, a problem of managing power stability may occur.

In particular, the inventors of the present disclosure have recognized that when the amount of calculations greatly increases in a specific layer, peak power consumption increases, thereby deteriorating system stability.

For example, many processing elements may be operated at the same time for the operation of a specific layer. A certain amount of power is required to drive each processing element, and when a considerable number of processing elements are simultaneously driven, the required power may rapidly increase. If the neural processing unit is designed specifically for low-power operation, the power supply capability may be relatively less than that of the neural processing unit for a server. Accordingly, such a neural processing unit for an edge device may be relatively more vulnerable to an instantaneous power supply issue, and a supply voltage may fluctuate when the power supply amount increases exponentially. Thus, data stored in the transistor may be lost, especially if the supply voltage drops below the threshold voltage of the transistor. In other words, when the supply voltage is lowered, setup/hold violation problems may occur in the neural processing unit, resulting in malfunction.

For another example, the inventors of the present disclosure have recognized that since the plurality of PEs 110 that perform operations for an artificial neural network, for example, add, multiply, and accumulate instantaneously consume a lot of power, sufficient power may not be supplied to other components in the NPU, for example, the internal memory 120. Specifically, the inventors of the present disclosure have recognized that there may be a problem that cannot be ruled out that, if sufficient power is not supplied to the internal memory 120, the possibility of compromising stored data bits may occur.

<Disclosures of the Present Disclosure>

The inventors of the present disclosure have recognized that the above-mentioned problem may be occurred due to a clock signal supplied to a hardware for performing calculations of the artificial neural network model.

Therefore, the inventors of the present disclosure propose a technique to solve the above problem by dividing the clock signal into several portions and then distributing operations of the artificial neural network model based on the various portions of the clock signal.

The examples in which the techniques disclosed by the inventors of the present disclosure will be described with reference to the drawings.

FIG. 7A is an exemplary diagram showing the structure of an NPU according to an example of the first disclosure of the present disclosure.

FIG. 7A illustrates that the NPU 100 may include a first group of PEs 110 g-1, a second group of PEs 110 g-2, an internal memory 120, an SFU 150, and a clock generator 190. However, the NPU 100 may further include an NPU controller 130 and an NPU interface 140 as shown in FIG. 3 or 5 . Each of the PEs 110 g-1 of the first group, the PEs 110 b of the second group, the internal memory 120, the NPU controller 130, the NPU interface 140, the SFU 150, and the clock generator 190 may be a semiconductor circuit to which numerous transistors are connected. Accordingly, some of them may be difficult to discern and distinguish with the naked eye, and may only be identified by its functions. The clock generator 190 may be referred to as a clock signal supply circuit.

For example, an arbitrary circuit may operate as a plurality of processing elements 110 or as an NPU controller 130.

The first group of PEs 110 g-1 and the second group of PEs 110 g-2 shown in FIG. 7A should be understood as being divided into a plurality of PEs 110 shown in FIG. 3 or 5 . Although the number of PEs belonging to each group is illustrated as eight groups as an example in FIG. 7A, and it will be apparent that the number of PEs belonging to each group may vary. In addition, the number of PEs allocated to each group can be changed semi-fixedly or dynamically. For example, a first group of PEs may include ten of PEs, and a second group of PEs may include six of PEs. This change may be performed under the control of the NPU controller 130.

The clock generator 190 shown in FIG. 7A may include an oscillator. Also, the oscillator may include a pulse width modulator (PWM). The PWM may adjust the duty ratio of the high signal and the low signal by changing the duty cycle of the clock cycle.

When the clock generator 190 generates and outputs a signal, it may be transmitted to the PEs 110 g-1 of the first group and the PEs 110 g-2 of the second group.

At this time, the PEs 110 g-1 of the first group are set to operate based on the first part (eg, rising edge) of the clock,

The second group of PEs 110 g-2 may be set to operate based on the second part (eg, falling edge) of the clock.

At this time, the first group of PEs 110 g-1 may be set to operate based on the first portion (e.g., rising edge) of the clock, and the second group of PEs 110 g-2 may be set to operate based on the second portion (e.g., falling edge) of the clock.

When the plurality of PEs 110 shown in FIG. 3 or 5 are divided into a first group of PEs 110 g-1 and a second group of PEs 110 g-2 as shown in FIG. 7A, and the first group of PEs 110 g-1 and the second group of PEs 110 g-2 operates based on different portions of the clock signal, the peak power can be reduced.

FIG. 7B is an exemplary view showing the structure of an NPU according to another example of the first disclosure of the present disclosure.

In FIG. 7B, the NPU 100 is illustrated as including a first group of PEs 110 g-1, a second group of PEs 110 g-2, an internal memory 120, and an SFU 150. In addition, the NPU 100 may further include an NPU controller 130 and an NPU interface 140 as shown in FIG. 3 or 5 . Each of the first group of PEs 110 g-1, the second group of PEs 110 g-2, the internal memory 120, the NPU controller 130, the NPU interface 140, and the SFUs 150 may be a semiconductor circuit in which numerous transistors are connected. Accordingly, some of them may be difficult to discern and distinguish with the naked eye, and may only be identified by operation thereof.

Referring to FIG. 7B, the clock generator 190 is shown to be located outside the NPU 100. Other than that, since it is the same as that shown in FIG. 7A, FIG. 7B will not be separately described, and the contents described with reference to FIG. 7A will be used as they are.

On the other hand, when the first group of PEs 110 g-1 and the second group of PEs 100 b shown in FIGS. 7A and 7B complete the operation of an arbitrary layer of the artificial neural network model,

The PEs 110 g-1 of the first group and the PEs 100 b of the second group output an operation result, that is, an output feature map according to one of the first part and the second part of the clock. To this end, at least one of the PEs 110 g-1 of the first group and the PEs 100 b of the second group may further include a time delay buffer (eg, a shift register). The time delay buffer (eg, shift register) may perform a time delay such that the output is performed according to a later part in time of the first part and the second part of the clock.

On the other hand, when the first group of PEs 110 g-1 and the second group of PEs 100 b shown in FIGS. 7A and 7B complete the operation of an arbitrary layer of the artificial neural network model, the first group of PEs 110 g-1 and the second group of PEs 110 g-2 may output an operation result, that is, an output feature map according to one of the first portion and the second portion of the clock. To this end, at least one of the first group of PEs 110 g-1 and the second group of PEs 110 g-2 may further include a time delay buffer (e.g., a shift register). The time delay buffer (e.g., shift register) may perform a time delay such that the output is performed according to a later portion in time of the first portion and the second portion of the clock signal.

For example, output ports of the second group of PEs 110 g-2 may be connected to a time delay buffer (e.g., a shift register). In this case, the delay buffer may perform a conversion from a first portion of the clock (e.g. a rising edge) to a second portion of the clock (e.g. a falling edge) or may perform conversion from the second portion of the clock (e.g., falling edge) to the first portion of the clock (e.g., rising edge).

Alternatively, the first group of PEs 110 g-1 shown in FIGS. 7A and 7B may output a first output feature map according to a first portion of the clock, and the second group of PEs 110 g-2 shown in FIGS. 7A and 7B may output the second output feature map according to the second portion of the clock. In this case, the SFU 150 may include a time delay buffer (e.g., a shift register). The SFU 150 may delay the received output feature map that has been received earlier than the other output feature map according to the first and second portion of the clock, thereby the intervals of the output feature maps can be synchronized with respect to the later portion of the first and second portion of the clock signal.

Alternatively, when the first output feature map output by the first group of PEs 110 g-1 and the second output feature map output by the second group of PEs 110 g-2 are not dependent on each other and are independent of each other, the SFU 150 may first process the received output feature map according to the earlier portion among the first portion and the second portion of the clock signal.

That is, the first output from the first group of PEs 110 g-1 and the second output from the second group of PEs 110 g-2 may be transmitted based on the first portion of the clock to the SFU 150.

The reference phase for the second group of PEs 110 g-2 may be converted from the second portion to the first portion of the clock.

The reference phases of the first group of PEs 110 g-1 and the second group of PEs 110 g-2 may be converted from the first portion of the clock (i.e., rising edge) to the second portion of the clock (i.e., falling edge) or may be converted from the second portion (i.e., falling edge) of the clock to the first portion (i.e., rising edge) of the clock.

Meanwhile, although not shown in FIGS. 7A and 7B, the SFU 150 may be electrically connected to the NPU internal memory 120.

On the other hand, although the NPU has been described in FIGS. 7A and 7B, the NPU may be implemented in a SoC form.

FIG. 8A is an exemplary diagram illustrating a structure of an SoC according to an example of the second disclosure of the present disclosure.

Referring to FIG. 8A, an exemplary SoC 1000 may include a plurality of NPUs, a plurality of central processing units (CPUs), and a plurality of memories. The plurality of NPUs may include, for example, a first NPU 100-1 and a second NPU 100-2. Also, the plurality of CPUs may include, for example, a first CPU 200-1 and a second CPU 200-2. The plurality of memories may include a first memory 300-1 and a second memory 300-2.

In FIG. 8A, the number of the plurality of NPUs, the plurality of CPUs, and the plurality of memories is shown as two, respectively, but is not limited thereto, and the number may be variously modified such as four, six, eight, and the like.

The exemplary SoC 1000 may include a memory controller 350, a clock generator 400, a system bus 500, and an input output (I/O) interface 800.

The system bus 500 may be implemented by an electrically conductive pattern formed on a semiconductor die. The system bus enables high-speed communication. For example, the plurality of NPUs, the plurality of CPUs, the plurality of memories, and the memory controller 350 may communicate with each other through the system bus 500.

The plurality of NPUs and the plurality of CPUs may read or write data from at least one of the plurality of memories by requesting the memory controller 350 through the system bus 500.

The clock generator 400 shown in FIG. 8A may include an oscillator. Also, the oscillator may include a pulse width modulator (PWM). The PWM can adjust the ratio of the high signal and the low signal by changing the duty cycle of the clock cycle.

When the clock generator 400 generates and outputs a signal, it may be transmitted to the first NPU 100-1 and the second NPU 100-2.

At this time, the first NPU 100-1 may be set to operate based on the first portion (e.g., rising edge) of the clock, and the second NPU 100-2 may be set to operate based on the second portion (e.g., falling edge) of the clock.

In this way, when the first NPU 100-1 and the second NPU 100-2 are distributed based on different portions of the clock, there is an advantage in that peak power can be reduced.

FIG. 8B is an exemplary diagram illustrating a structure of an SoC according to another example of the second disclosure of the present disclosure.

Referring to FIG. 8B, an exemplary SoC 1000 may include a plurality of NPUs, a plurality of central processing units (CPUs), and a plurality of memories. The plurality of NPUs may include, for example, a first NPU 100-1 and a second NPU 100-2. Also, the plurality of CPUs may include, for example, a first CPU 200-1 and a second CPU 200-2. The plurality of memories may include a first memory 300-1 and a second memory 300-2.

In FIG. 8B, the number of the plurality of NPUs, the plurality of CPUs, and the plurality of memories is shown as two, respectively, but is not limited thereto, and the number may be variously modified such as four, six, eight, and the like.

The exemplary SoC 1000 may include a memory controller 350, a clock generator 400, a plurality of buses, and an input output (I/O) interface 800.

The plurality of buses may include a bus for CPU, that is, a CPU bus 500-1, a bus for NPU, that is, a NPU bus 500-2, and a bus for peripheral components, that is, a peripheral bus 500-3.

The first CPU 200-1, the second CPU 200-2, and the first memory 300-1 may be connected to the CPU bus 500-1. A first NPU 100-1, a second NPU 100-2, and a second memory 300-2 may be connected to the NPU bus 500-2. A memory controller 350 and a clock generator 400 may be connected to the peripheral bus 500-3.

The clock generator 400 may include an oscillator. Also, the oscillator may include a pulse width modulator (PWM).

When the clock generator 400 generates and outputs a signal, it is transmitted to the first NPU 100-1 and the second NPU 100-2.

At this time, the first NPU 100-1 may be set to operate based on the first portion (e.g., rising edge) of the clock, and the second NPU 100-2 may be set to operate based on the second portion (e.g., falling edge) of the clock.

If the first NPU 100-1 and the second NPU 100-2 operate with distribution based on different portions of the clock, there is an advantage in that peak power can be reduced.

The above description is focused on the SoC, but the present disclosure is not limited to the SoC, and the content of the present disclosure can also be applied to a system in package (SiP) or printed circuit board (PCB) based board level system. For example, each functional component may be implemented as an independent semiconductor chip and connected to each other through a system bus implemented by an electrically conductive pattern formed on a PCB. More details will be described with reference to FIG. 9 .

FIG. 9A is an exemplary view showing the structure of a system according to an example of the third disclosure of the present disclosure.

Referring to FIG. 9A, an exemplary system 2000 may include a plurality of NPUs, a plurality of central processing units (CPUs), and a plurality of memories mounted on a substrate 900. The plurality of NPUs may include, for example, a first NPU 100-1 and a second NPU 100-2. Also, the plurality of CPUs may include, for example, a first CPU 200-1 and a second CPU 200-2. The plurality of memories may include a first memory 300-1 and a second memory 300-2.

In FIG. 9A, the number of the plurality of NPUs, the plurality of CPUs, and the plurality of memories is shown as two, respectively, but is not limited thereto, and the number may be variously modified such as four, six, eight, and the like.

The exemplary system 2000 may include a memory controller 350, a clock generator 400, a system bus 500, and an input output (I/O) interface 800.

The system bus 500 may be implemented by an electrically conductive pattern formed on the substrate 900. The system bus enables high-speed communication. For example, the plurality of NPUs, the plurality of CPUs, the plurality of memories, and the memory controller 350 may communicate with each other through the system bus 500.

The clock generator 400 shown in FIG. 9A may include an oscillator. Also, the oscillator may include a pulse width modulator (PWM). The PWM can adjust the ratio of the high signal and the low signal by changing the duty cycle of the clock cycle.

When the clock generator 400 generates and outputs a signal, it may be transmitted to the first NPU 100-1 and the second NPU 100-2.

At this time, the first NPU 100-1 may be set to operate based on the first portion (e.g., rising edge) of the clock, and the second NPU 100-2 may be set to operate based on the second portion (e.g., falling edge) of the clock.

In this way, when the first NPU 100-1 and the second NPU 100-2 operate with distribution based on different portions s of the clock, there is an advantage in that peak power can be reduced.

FIG. 9B is an exemplary view showing the structure of a system according to an example of the third disclosure of the present disclosure.

Referring to FIG. 9B, an exemplary system 2000 may include a plurality of NPUs, a plurality of central processing units (CPUs), and a plurality of memories mounted on a substrate 900. The plurality of NPUs may include, for example, a first NPU 100-1 and a second NPU 100-2. Also, the plurality of CPUs may include, for example, a first CPU 200-1 and a second CPU 200-2. The plurality of memories may include a first memory 300-1 and a second memory 300-2.

In FIG. 9B, the number of the plurality of NPUs, the plurality of CPUs, and the plurality of memories is shown as two, respectively, but is not limited thereto, and the number may be variously modified such as four, six, eight, and the like.

The exemplary system 2000 may include a memory controller 350, a clock generator 400, a plurality of buses, and an input output (I/O) interface 800.

The plurality of buses may be implemented by an electrically conductive pattern formed on the substrate 900.

The plurality of buses may include a bus for CPU, that is, a CPU bus 500-1, a bus for NPU, that is, a NPU bus 500-2, and a bus for peripheral components, that is, a peripheral bus 500-3.

The first CPU 200-1, the second CPU 200-2, and the first memory 300-1 may be connected to the CPU bus 500-1. A first NPU 100-1, a second NPU 100-2, and a second memory 300-2 may be connected to the NPU bus 500-2. A memory controller 350 and a clock generator 400 may be connected to the peripheral bus 500-3.

The clock generator 400 may include an oscillator. Also, the oscillator may include a pulse width modulator (PWM).

When the clock generator 400 generates and outputs a signal, it may be transmitted to the first NPU 100-1 and the second NPU 100-2.

At this time, the first NPU 100-1 may be set to operate based on the first portion (e.g., rising edge) of the clock, and the second NPU 100-2 may be set to operate based on the second portion (e.g., falling edge) of the clock.

If the first NPU 100-1 and the second NPU 100-2 operation with distribution based on different portions of the clock, there is an advantage in that peak power can be reduced.

FIG. 10 is an exemplary diagram illustrating an operation method of an NPU according to the disclosures of the present specification.

Referring to FIG. 10 , a driving signal for driving a plurality of PEs may be generated S1010.

The plurality of PEs may be divided into PEs of a first group and PEs of a second group S1020. It will be apparent that the number of PEs belonging to each group may vary. In addition, the number of PEs belonging to each group can be changed semi-fixedly or dynamically. This change may be performed under the control of the NPU controller 130.

Then, based on the first portion of the clock signal, the PEs of the first group may be driven S1030. Also, based on the second portion of the clock signal, the PEs of the second group may be driven S1040.

FIG. 11 is an exemplary diagram illustrating an operation method of an NPU according to the disclosures of the present specification.

Referring to FIG. 11 , a driving signal for driving a plurality of NPUs may be generated S1110.

The plurality of NPUs may be divided into a first group of NPUs and a second group of NPUs S1120. It will be apparent that the number of NPUs belonging to each group may vary. In addition, the number of NPUs belonging to each group may be changed semi-fixedly or dynamically. This change may be performed under the control of the CPU.

Then, based on the first portion of the clock signal, the first group of NPUs may be driven S1130. Also, based on the second portion of the clock signal, the NPUs of the second group may be driven S1140.

According to an example of the present disclosure, a system is provided. The system may comprise a neural processing unit (NPU) including at least one memory and a plurality of processing elements (PEs) capable of performing operations for at least one artificial neural network (ANN) model. The plurality of PEs may include an adder, a multiplier, and an accumulator. The plurality of PEs may include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.

According to an example of the present disclosure, a SoC is provided. The SoC may comprise a first circuit arranged as at least one memory; and a second circuit arranged as a plurality of processing elements (PEs) capable of performing operations for at least one of artificial neural network (ANN) models. The plurality of PEs may include an adder, a multiplier, and an accumulator. The plurality of PEs may include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.

According to an example of the present disclosure, a method is provided. The method of operating a NPU may comprise generating a clock signal for driving the NPU including a plurality of processing elements (PEs); operating a first group of PEs of the plurality of PEs on a first portion of the clock signal; and operating a second group of PEs of the plurality of PEs on a second portion of the clock signal. The plurality of PEs may include an adder, a multiplier, and an accumulator.

Examples of the present disclosure described in the present disclosure and drawings are merely presented as specific examples to easily explain the technical content of the present disclosure and help understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. It is apparent to those of ordinary skill in the art that other modified examples can be implemented or derived in addition to the examples described.

[National R&D Project Supporting This Invention]

[Task Identification Number] 1711193247

[Task Number] 2022-0-00248-002

[Name of Ministry] Ministry of Science and ICT

[Name of Project Management (Specialized) Institution] Institute of Information & Communications Technology Planning & Evaluation

[Research Project Title] Development of Core Technology for PIM Artificial Intelligence Semiconductor (Design)

[Research Task Title] Development of CXL-based PIM semiconductor technology for multiple DRAM modules considering memory consistency

[Contribution Rate]1/1

[Name of Organization Performing the Task] DeepX Co., Ltd.

[Research period 15 minutes] 2023-01-01-2023-12-31 

What is claimed is:
 1. A system comprising: a neural processing unit (NPU) including at least one memory and a plurality of processing elements (PEs) capable of performing operations for at least one artificial neural network (ANN) model, wherein the plurality of PEs include an adder, a multiplier, and an accumulator, and wherein the plurality of PEs include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.
 2. The system of claim 1, wherein the first portion is a rising edge of the clock signal, and the second portion is a falling edge of the clock signal.
 3. The system of claim 1, wherein a first output from the first group of PEs and a second output from the second group of PEs are transmitted based on the first portion of the clock signal.
 4. The system of claim 2, wherein at least one reference phase of at least one group of the first group of PEs and the second group of PEs is converted from the rising edge to the falling edge of the clock signal or converted from the falling edge to the rising edge of the clock signal.
 5. The system of claim 1, wherein a reference phase of the second group of PEs is converted from the second portion to the first portion of the clock signal.
 6. The system of claim 2, wherein an output port of the second group of PEs is connected to a delay buffer, and wherein the delay buffer is configured to perform conversion from the rising edge to the falling edge of the clock signal or from the falling edge to the rising edge of the clock signal.
 7. The system of claim 1, wherein an output port of the second group of PEs is connected to a delay buffer, and wherein the delay buffer is configured to convert the second portion of the clock signal to the first portion of the clock signal or convert the first portion of the clock signal to the second portion of the clock signal.
 8. The system of claim 1, wherein the NPU further includes a special function unit (SFU) connected to output ports of the PEs of the first and second groups.
 9. The system of claim 8, wherein the SFU is coupled to the at least one memory.
 10. The system of claim 1, wherein the plurality of PEs of the first and second groups are time-varying.
 11. A system on chip (SoC) comprising: a first circuit arranged as at least one memory; and a second circuit arranged as a plurality of processing elements (PEs) capable of performing operations for at least one of artificial neural network (ANN) models, wherein the plurality of PEs include an adder, a multiplier, and an accumulator, and wherein the plurality of PEs include a first group of PEs configured to operate on a first portion of a clock signal and a second group of PEs configured to operate on a second portion of the clock signal.
 12. The SoC of claim 11, wherein the first portion is a rising edge of the clock signal, and the second portion is a falling edge of the clock signal.
 13. The SoC of claim 11, wherein a first output from the first group of PEs and a second output from the second group of PEs are transmitted based on the first portion of the clock signal.
 14. The SoC of claim 12, wherein at least one reference phase of at least one group of the first group of PEs and the second group of PEs is converted from the rising edge to the falling edge of the clock signal or converted from the falling edge to the rising edge of the clock signal.
 15. The SoC of claim 11, wherein a reference phase of the second group of PEs is converted from the second portion to the first portion of the clock signal.
 16. The SoC of claim 12, wherein an output port of the second group of PEs is connected to a delay buffer, and wherein the delay buffer is configured to perform conversion from the rising edge to the falling edge of the clock signal or from the falling edge to the rising edge of the clock signal.
 17. The SoC of claim 11, wherein an output port of the second group of PEs is connected to a delay buffer, and wherein the delay buffer is configured to convert the second portion of the clock signal to the first portion of the clock signal or convert the first portion of the clock signal to the second portion of the clock signal.
 18. A method of operating a neural processing unit (NPU) comprising: generating a clock signal for driving the NPU including a plurality of processing elements (PEs); operating a first group of PEs of the plurality of PEs on a first portion of the clock signal; and operating a second group of PEs of the plurality of PEs on a second portion of the clock signal, wherein the plurality of PEs include an adder, a multiplier, and an accumulator.
 19. The method of claim 18, wherein the first portion is a rising edge of the clock signal, and the second portion is a falling edge of the clock signal.
 20. The method of claim 18, wherein a first output from the first group of PEs and a second output from the second group of PEs are transmitted based on the first portion of the clock signal. 